Filter apparatus and frequency converter to which the filter apparatus is connected

ABSTRACT

A power converter in which a filter apparatus is connected to a wiring drawing portion, said filter apparatus including: a condenser element having an electronic part having an insulator as a dielectric material held between conductor plates; a sealing agent sealing said condenser element; a filter circuit comprising said condenser element; a connection conductor establishing wiring connections of said filter circuit; and a filter housing supporting said sealing agent.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 10/985,943, filedNov. 12, 2004. This application relates to and claims priority fromJapanese Patent Application No. 2003-384487, filed on Nov. 14, 2003. Theentirety of the contents and subject matter of all of the above isincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a technique for reducing noises of afrequency converter supplying electric power to, for example, a motor.

PRIOR ART

For specifications regarding electromagnetic noises in the frequencyconverter, performance characteristics for which the CE mark can belabeled, EN55011 (Class A, Class B) and EN61800 are known. Thespecifications and the like are described for specifying limit values ofelectromagnetic noises according to apparatuses used and classes of useenvironments to prevent influences on other electrical apparatuses.

Techniques regarding measures against noises as described above include,for example, the technique disclosed in Patent Document 1.

[Patent Document 1] JP-A-8-308250

In measures against noises, a filter apparatus reducing electromagneticnoises and the like is generally provided. However, if the filterapparatus is provided, a mounting space is required accordingly, and thedrawing of wiring and the like for connecting the filter apparatusshould be considered.

In view of the matters described above, the object of the presentinvention is to provide a filter apparatus reducing electromagneticnoises and the like for a frequency converter supplying electric powerto, for example, a motor, and to realize a downsizing and the like ofthe frequency converter or filter apparatus while connecting the filterapparatus to the frequency converter.

BRIEF SUMMARY OF THE INVENTION

The present invention solves the above problem as follows. A filterapparatus reducing electromagnetic noises and the like is provided neara wiring drawing portion of a main circuit terminal board of a frequencyconverter.

The filter apparatus is connected to the wiring drawing portion of themain circuit terminal board.

Part of a housing of the frequency converter and part of a filterhousing are fitted to each other to fix the filter housing on thefrequency converter.

Characteristics of the filter apparatus may be defined as not havinginfluences such as electromagnetic noises on other electric apparatusesbased on performance characteristics for which the CE mark can belabeled, EN55011 and the specification of EN61800, for example.

Particularly, the specification of EN61800 and EN55011 (Class A, ClassB) included in the specification of EN 61800 are generally well known inthe frequency converter and the like.

Thus, as a filter apparatus reducing electromagnetic noises and thelike, the filter apparatus may be configured to have characteristics offilter apparatus based on the specification of EN61800 and EN55011(Class A, Class B) included in the specification of EN61800.

According to the present invention, a product having goodcharacteristics can be provided as to reduction of noises of thefrequency converter. Alternatively, a frequency converter having areduced size while achieving a reduction in noises can be provided.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows an example of a frequency converter having anelectromagnetic noise filter mounted thereon;

FIG. 2 shows another example of the frequency converter having theelectromagnetic noise filter mounted thereon;

FIG. 3 shows Example of the present invention (plan view);

FIG. 4 shows Example of a waterproof case of a digital operator;

FIG. 5 shows Example of the electromagnetic noise filter (sectionalview);

FIG. 6 shows Example of the electromagnetic noise filter (anothersectional view); and

FIG. 7 shows an example of another method for mounting theelectromagnetic noise filter.

DETAILED DESCRIPTION OF THE INVENTION

An electromagnetic noise filter as a filter apparatus reducingelectromagnetic noises in Example according to the present invention, ora frequency converter to which the filter apparatus is connected will bedescribed in detail below using Example shown in figures.

FIG. 1 shows an implementation of the electromagnetic noise filter asExample according to the present invention. In the figure, referencenumeral 1 denotes a frequency converter housing, reference numeral 2denotes an electromagnetic noise filter case, reference numeral 3denotes a terminal board cover, reference numeral 4 denotes a wiringdrawing plate, and reference numeral 5 denotes an earth bar forfrequency converters. The frequency converter housing 1 is provided witha groove 6 for mounting the wiring drawing plate 4, and the wiringdrawing plate 4 is provided with a raised portion 7. The electromagneticnoise filter case 2 is also provided with the raised portion 7. If nofilter is required, the electromagnetic noise filter case 2 can beremoved to fit the wiring drawing plate 4 directly into the groove 6provided in a case of the frequency converter 1.

Attachment/detachment can be eased by providing a raised portion 22 onthe side face of the electromagnetic noise filter case 2 and providing arecessed portion 21 on the side face of the frequency converter housing1 as shown in FIG. 7. The recessed portion 21 is a hole-like portionprovided on the side face of the frequency converter housing 1, and theraised portion 22 is a protruding portion provided on the side face ofthe electromagnetic noise filter case 2. The recessed portion 21 and theraised portion 22 are fitted to or engaged with each other to fix theelectromagnetic noise filter case 2 to the frequency converter housing1.

In the configuration shown in FIG. 1, the frequency converter housing 1and the filter housing of the electromagnetic noise filter case 2 arefitted to each other to fix the electromagnetic noise filter to thefrequency converter. For this purpose, a fitting portion fitting part ofthe frequency converter housing 1 and the filter housing of theelectromagnetic noise filter case 2 to each other is provided in eachhousing.

In FIG. 1, the recessed groove 6 for mounting the wiring drawing plate 4in the frequency converter housing 1 or the raised portion 7 in theelectromagnetic noise filter case 2 is the fitting portion. However, thefitting portion is not limited to the specific shape of the recessedgroove 6 or raised portion 7, but may have any different shape asappropriate as long as it allows the frequency converter housing 1 to befixed to the filter housing of the electromagnetic noise filter case 2.

Example of fixation by fitting has been described above, but fixation isnot limited thereto, and part of the frequency converter housing 1 andpart of the filter housing of the electromagnetic noise filter case 2may be interlocked or engaged with each other for fixation. In thiscase, an interlocking portion interlocked with part of each housing oran engagement portion engaging parts of the housings with each other isprovided.

If a filter having better characteristics or a filter having a largersize is required for making the filter compliant with a higherspecification in terms of the specification, the attached filter can beremoved to attach a filter for the specification with ease in the mannerdescribed above.

Alternatively, a noise filter effect can be increased by couplingtogether electromagnetic noise filter cases 2 having the same shape asshown in FIG. 2. In this case, the fitting portion composed of therecessed portion 21 and the raised portion 22 is provided in theelectromagnetic noise filter case 2, thus making it possible to coupletogether electromagnetic noise filter cases 2 at the fitting portioncomposed of the recessed portion 21 and the raised portion 22.

The coupled noise filter cases may be different in size, thickness,characteristics of filters, contained condensers, electronic partsconstituting the filter, and the like. However, by equalizing the outerdimensions of electromagnetic noise filter cases, the overalldimensional and the like as the frequency converter can be approximatelyestimated to afford convenience during installation in equipment as amatter of course.

A fixing screw for installing the electromagnetic noise filter is notrequired because the groove 6 provided originally for use in thefrequency converter is used, and thus the need for screws can beeliminated for fixation.

However, for fixing the electromagnetic noise filter case 2 to thefrequency converter housing 1, a screw may be used, or an adhesive orHook-and-Loop fastener (detachable plane fastener with a hook shape anda pile shape interlocked) may be used.

In this case, positioning for positioning the electromagnetic noisefilter case 2 at a predetermined location in the frequency converterhousing 1 can be considered. For example, a positioning portion isprovided in part of the frequency converter housing 1, and theelectromagnetic noise filter case 2 is positioned based on thepositioning portion and is then fixed with the screw or the like,whereby efficiency of fixation work and the like can be improved.

For the positioning portion, a portion such as the recessed portion 21or raised portion 22 described with FIG. 2 may be used as a positioningportion. Alternatively, positioning may be done by protruding a heatdissipation fin 30 shown in FIG. 7 by a predetermined length relative tothe frequency converter housing 1 and abutting part of theelectromagnetic noise filter case 2 against the protruding portion. Ofcourse, positioning may be done by providing a protruding portion inpart of the frequency converter housing 1 and abutting part of theelectromagnetic noise filter case 2 against the protruding portion.

The location in the frequency converter housing 1 at which theelectromagnetic noise filter case 2 is mounted, shown in FIG. 1, is alocation at which a space must be usually provided for wiring to thefrequency converter such as main circuit wiring. For this reason, it isnot required to provide a space for mounting the electromagnetic noisefilter case in the frequency converter housing 1.

Thus, the frequency converter housing 1 is never upsized even if theelectromagnetic noise filter case is mounted. The shape of the frequencyconverter housing 1 should not be changed between a type of frequencyconverter in which the electromagnetic noise filter case is mounted anda type of frequency converter in which electromagnetic noise filter caseis not mounted. That is, regardless of whether the electromagnetic noisefilter case is mounted or not, the shape of the frequency converterhousing 1 can be equalized. This contributes to reduction in costs formoldings that are used during production of the frequency converterhousing 1, and the like.

A view seen from the top is shown in FIG. 3. From the electromagneticnoise filter case 2, terminals 8, 9 and 10 are connected to inputterminals R, S and T, respectively. The terminals 8, 9 and 10 are madeof conductive materials such as metals such as copper, aluminum andcopper-nickel alloys.

The terminals 8, 9 and 10 are made of thin metal and therefore, even ifa slight difference in height occurs during connection to a terminalboard provided in the frequency converter 1, the material is warped anddeformed to make connection easy. The terminals 8, 9 and 10 areconductive plates in the figure, but the same effect can be obtained ifthey are wire rods.

A sectional view of the electromagnetic noise filter case is shown inFIG. 6. Another sectional view of the electromagnetic noise filter caseis shown in FIG. 7. Inside the electromagnetic noise filter case 2, afilter condenser 11 is placed and walls 12 and 13 for partitioning thefilter condenser 11 are provided. The filter condenser 11 is usuallycovered with a resin 23 of plastic as a sealing agent for ensuringimprovement in moisture resistance and heat resistance and an insulationdistance specified in the specification, and is thus unseen afterassembly.

Usually, the filter condenser 11 that is used in Example does not have acase that is provided when the condenser is formed. A usual condenserhas electronic parts composed of metal plates and an insulator or thelike as a dielectric material held between the metal plates covered witha condenser case. In Example, the electronic part composed of metalplates and an insulator or the like as a dielectric material heldbetween the metal plates is placed directly in the noise filter case 2and covered with the resin 23 of plastic. With this configuration, thefilter can be downsized and lightened as a whole because the usualcondenser is absent.

A groove 15 through which an earth bar 14 for filter condenser connectedto the earth bar 5 for frequency converter passes. The wall 13 providednear the groove 15 is made to be little taller than the wall 12partitioning the condenser 11, whereby the resin of plastic is preventedfrom flowing into the groove 15 even if a low-viscosity plastic resin isused when the filter condenser 11 is covered with the resin 23 ofplastic. As a result, even if a low-viscosity resin not requiring adegassing apparatus or the like is used, the plastic resin is neverleaked from the groove into which the earth bar 14 being a connectionconductor on the ground side is fitted, and thus workability isimproved.

When a high-viscosity plastic resin is used, the groove 15 is made tohave an appropriate size, whereby the plastic resin used for sealing thefilter condenser 11 is never leaked from the groove 15 owing to theviscosity of the plastic resin, thus making it possible to eliminate theneed for the wall 13.

The earth bar 5 for frequency converter and the earth bar 14 for filtercondenser are connected directly on the undersurface of theelectromagnetic noise filter case 2, or connected through a conductorplate or wire rod. As in the connection form described above, theconnection conductor on the ground side of the electromagnetic noisefilter case 2 should be connected to the connection conductor on theinstallation side of the frequency converter at a shortest possibledistance.

The conductor plate 20 grounding the filter condenser 11 on the groundside inside the electromagnetic noise filter case 2 is placed along theinner wall of the electromagnetic noise filter case 2, wherebyelectromagnetic noises generated in the electromagnetic noise filtercase 2 can be blocked.

A volume control knob 17 placed in the frequency converter 1 andprovided in a digital operator 16 can easily be attached and detached.

The digital operator 16 is held between a waterproof cover 19 and awaterproof case 18 as shown in FIG. 4, whereby waterproof measures canbe made.

The filter apparatus and the frequency converter in the Exampledescribed above may be, for example, distributed, sold, and transferredin the market and the like with each of them as a single product.Alternatively, they may be, for example, distributed, sold andtransferred in the market and the like as the frequency converter withthe filter apparatus connected thereto, i.e. in an integrated state.

For a condenser element that is used in the filter apparatus in theExample described above, a condenser element having an electronic parthaving an insulator as a dielectric material held between conductorplates can be used.

Characteristics of the filter apparatus may be defined as not havinginfluences such as electromagnetic noises on other electricalapparatuses and the like based on, for example, the CE specification,EN55011 and the specification of EN61800.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A power converter in which a filter apparatus is connected to awiring drawing portion, said filter apparatus comprising: a condenserelement having an electronic part having an insulator as a dielectricmaterial held between conductor plates; a sealing agent sealing saidcondenser element; a filter circuit comprising said condenser element; aconnection conductor establishing wiring connections of said filtercircuit; and a filter housing supporting said sealing agent.
 2. Thepower converter according to claim 1, wherein the connection conductordrawn from a side opposite to an opening of said filter housing isconnected to the frequency converter on the ground electrode side. 3.The power converter according to claim 1, wherein the connectionconductor drawn from a side opposite to a side on which the connectionconductor is connected to the wiring drawing portion of said frequencyconverter is connected to the frequency converter on the groundelectrode side.
 4. The power converter according to claim 1, whereinsaid connection conductor covers part of the side face inside saidfilter housing.
 5. The power converter according to claim 1, wherein awall for preventing said sealing agent from flowing out from a hole fortaking the connection conductor on the ground side which is connected tosaid frequency converter on the ground electrode side is provided. 6.The power converter according to claim 5, wherein if said sealing agenthas a high viscosity, a wall for preventing said sealing agent fromflowing out from a hole for taking the connection conductor on theground side which is connected to said frequency converter on the groundelectrode side is not provided.
 7. The power converter according toclaim 1, wherein part of a housing of said frequency converter and partof the filter housing are fitted to each other to fix said filterhousing to said frequency converter.
 8. The power converter according toclaim 1, wherein the filter housing is provided with a fitting portionin which part of the filter housing is fitted to part of the housing ofsaid frequency converter.
 9. The power converter according to claim 8,wherein the filter housing is provided with a raised portion fitted to arecessed groove in part of the housing of said frequency converter. 10.The power converter according to claim 8, wherein the filter housing isprovided with a recessed groove fitted to a raised portion in part ofthe housing of said frequency converter.
 11. The power converteraccording to claim 1, wherein characteristics of said filter apparatusare based on Class A of EN55011, Class B of EN55011 or the specificationof EN61800.